VOLTAGE SWITCHING CIRCUIT AND SEMICONDUCTOR MEMORY

摘要

PURPOSE:To prevent the drop of an output voltage by using an enhancement type MOS transistor for a first MOS transistor, and supplying a voltage exceeding a program voltage value to a gate of the transistor. CONSTITUTION:An enhancement type is used as a MOS transistor TR Q4 for switching a voltage, and a gate voltage VG of its TR Q4 is made higher than a program voltage Vpp (for instance, VG>Vpp+Vth) (Vth denotes a threshold voltage). According to this constitution, by using the enhancement type for the TR Q4 for supplying a first power supply voltage Vpp, a turn-off state is maintained at the time of a gate - source voltage VGS=0, therefore, generation of a through-current I can be prevented. In addition, since the gate voltage VG of the TR Q4 is made higher than the voltage Vpp by a voltage supply means 100, a drop of an output voltage VOUT caused by a voltage drop of a threshold voltage Vth portion which occurs in the TR Q4 can be prevented.